Yes, I was in Dialog Test for hours & hours, before posting the board. And I read thru several online manuals. I used 'executil ts' to do tracing, since I executed the COBOL program from within a small REXX EXEC. Your 'TSO ISPVCALL' provides an interesting audit trail.

But in Dialog Test or in using either trace, I still find no clue as to why I cannot change the Working-Storage variables that are displayed on the screen. Perhaps the fact that I execute the program from within REXX has something to do with it, I don't know.

The strange part of it is that the variables will display at their initial value in Working-Storage - the screen will not be blank when displayed. But then when I change the values of those variables, the old beginning values stay on the screen.